1. Field of the Invention
This invention relates to and has among its objects the provision of novel antihemophilic factor concentrates and methods for making them. Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless specified otherwise.
2. Description of the Prior Art
Currently, antihemophilic factor (AHF), otherwise known as Factor VIII, is prepared from human plasma. Cryoprecipitate is recovered from thawed pools of fresh frozen human plasma by centrifugation and diced and washed to remove soluble proteins. Then, the cryoprecipitate is extracted or solubilized with water. The pH of the aqueous solution is adjusted to slightly acid and the solution is chilled to separate extraneous non-AHF protein. Next, the aqueous solution is treated with aluminum hydroxide to further remove unwanted protein, particularly prothrombin complex proteins. This purification technique using aluminum hydroxide has been described by Hershgold et al in J. Lab & Clin. Med., 1966, Vol. 67, pages 23-32, by Mozen at the Twenty-Fourth Annual Wayne State University Symposium on Blood, Detroit, Michigan (January 1976) and at the XV Congress of the International Society of Hematology, Jerusalem, Israel (1974), and by Liu et al, U.S. Pat. No. 4,170,639 (October 1979). Salt and a buffer are added to the aqueous solution which is then freeze-dried after adjustment of the pH of the aqueous solution to slightly acid.
In large scale processing, it is desirable to remove water from the aqueous AHF solution prior to freeze-drying it. To this end the AHF concentrate is reprecipitated before it is lyophilized. The aqueous solution is treated with either cold ethanol, polyethylene glycol, or glycine which results in precipitation of AHF proteins. The precipitate is collected by centrifugation, mixed with water buffer, saline, and acid, and freeze-dried.
Liu, in U.S. Pat. No. 4,170,639, discloses that an aqueous AHF extract, after purification with aluminum hydroxide and reconstitution with buffer and saline and adjustment to an acidic pH, may be subjected to ultrafiltration to concentrate it prior to freeze-drying. The ultrafiltration is conducted only on reconstituted AHF extract that has been adjusted to an acidic pH using a membrane with a molecular weight cut-off of one million daltons.